New lactone



United States Patent NEW LACTONE Reginald John William Reynolds and Edward Jervis Vlckers, 'Manchester, England, assignors to Imperial Chemical Industries Limited, London, England, a corporation of Great Britain No Drawing. Application August 23, 1955 Serial No. 530,200

Claims priority, application Great Britain August 4, 1955 g 3 Claims. Cl. 260-783) This invention relates to a new lactone useful for the manufacture of polyesters and to its manufacture.

According to the invention there is provided aim-bisof 5:5:18"-trichloropivalic acid, when practically pure lactone is obtained as the distillate. Silver and lead salts of fl:fl:fi"-trichloropivalic acid are particularly advantageous to use, in that the yields of aza-bis-(chloromethyn- B-propiolactone so obtained are practically quantitative.

Polyesters having'the structural unit:

C HgCl v Olh- -000- 011,01 may be made by polymerising a:a-bis-(chloromethyD-ppropiolactone, advantageously in presence of catalysts for the polymerisation.

As catalysts there may be used, for example acids such as sulphuric acid or bases such as the alkali-metal hydroxides or alkoxides, and tertiary amines such as triethylamine, dimethylaniline, N:N:N:N'-tetramethylhexamethylen'ediarnine orhexamethylenetetramine. Friedel- Crafts catalysts and their complexes, for, example ferric chloride, aluminium chloride'a'nd boron trifiuoride diethyl the melt becomes more viscous, and on cooling solidifies ICC out at a temperature above the melting point of the aza-bis-(chloromethyl)fi-propiolactone. In general temperatures between 0 and 100 C. have been found suitable.

The presence of water during polymerisation may in some cases be detrimental to the production of high molecular weight. polymers; for example, when tertiary amines are employed as catalysts, the presence of relatively small amounts of water leads to the formation of lower molecular weight products. Accordingly, in general, wherehigh molecular Weight polymers are desired anhydrous conditions are preferred.

When only low molecular weight polymers are desired, these may be obtained directly from salts of B:;8':l3"- trichloropivalic acid. For example, from aqueous solutions of such salts, particularly concentrated solutions either at room temperature or at elevated temperatures, polymer is deposited directly after about an hour at roomtemperature, or more rapidly at elevated temperatures. When such low molecular weight polymers are heated above the melting point, further condensation takes place,

to give a glassy resin.

The polyesters may contain other structural units in addition to the unit:

H201 I 3 Such polyesters may be made, for example, by copolymerisation of octet bis (chloromethyl)- 3-propiolactone with other p-lactones havingthev general formula:

iii

ethera'te may be used. Certain salts which are able to i react with the fl-lactone after the manner where M+ is a metal cation and X the accompanying anion, for example salts of carboxylic acids, or metal phenoxides, are also useful catalysts. Quaternary ammonium compounds may also be used with particular advantage where the corresponding metal compounds are characterised by low solubility in the monomeric aza-bis- (chloromethyl)fl-propiolactone; thus for example quaternary ammonium halides are generally much more efiective as catalysts than the corresponding alkali metal halides. These catalysts are used in small amount, preferably from about 0.01 to 0.50 molar percent.

The polymerisation may be carried out, if desired, in the presence of inert solvents or diluents. Examples of such solvents or diluents, which are inert to mica-bis- (chloromethyl)fi-propiolactone, are cyclohexane, toluene, chlorobenzene, nitrobenzene and acetonitrile.

The temperature of polymerisation depends upon the activity of the catalyst. Also, if solvents or diluents are not used, it is preferred that polymerisation be carried -.-'-'CO v where R ,R'*,R and R may be hydrogen or hydrocarbo residues, for example B-propiolactone, a-methyl-fl-propio lactone, a-ethyl-B-rnethyl-fi-propiolactone, Bzfl-dirnethylfl-propiolactone, and at:ot-diphenyl-pt-propiolactone. When high molecular weight polymers are required itis' preferred that at least R and R be hydrocarbon residues; Particularly useful polymers are obtained by copol'ymeri-f sation of a:a-bis-(chloromethyl)B-propiolzictone with a:u-dimethyl-fi-propiolactone.

Besides fi-lactones, other 'polymerisable cyclic esters may be used in copolymerisation with am-bis-(chloro' methyD-fi-propiolactone, for example diglycollide.

The polyesters, including co-polyesters, are particularly useful for the manufacture of moulded articles, fibres and films. A particular feature of polymers containing in major amount the structural unit:

cmci CHzcoo- H201 is their high melting point. Hitherto aliphatic polyesters have generally been characterised by comparatively low melting points.

The invention is illustrated but not limited by the following examples in which the parts and percentages are by Weight:

Example 1 The anhydrous, finely-powdered silver salt of 5:519"- trichloropivalic acid is heated cautiously in an oil-jacketed distillation unit in a slow stream of nitrogen at a pressure of 0.2-0.3 mm. of mercury. A liquid begins to distil slowly when the jacket temperature reaches C. and somewhat more rapidly when the temperature reaches C. The liquid distillate soon begins to crystallise in the receiver. The jacket temperature is maintained Patented Sept. 23, 1958 3 between 110 C. and 115 C. until distillation slackens and is then raised slowly to 150 C. Very little further distillation occurs above a jacket temperature of 125 C. The soliddistillate is collected and consists of practicallypure wza-bis-(chloromethyl)-B-propiolactone melting at 3536 C. The melting-point is unchanged after recrys-. tallisation from a mixture of n-hexane and benezene. Elementary analysisgives afi'gure of 42 .4% for'chlorine content (theory 42.0%).

'When the a!a-biS-(ChIOI'OmGthYI),BpIOplOl8.CtO116 so obtained is heated above its melting point with a trace amount ofpyridine, rapid polymerisation occurs to give a polymer which showssome signs of sintering at 250 C. but only melts completely at about 295 C.

- Example- 2 The. anhydrous finely powdered lead salts of 3:525"- trichloropivalicacid is heated cautiously in an oil-jacketed distillation unit in a slow stream of nitrogen at a pressure of- 0.3-0.4 mm. of mercury. A liquid distillate, which crystallises in the cold receiver, begins to appear when the jacket temperature reaches about 165 C. The temperature is raised further to about 195 C. and is maintained at between 195-200 C. until distillation ceases. The solid distillate in the receiver is dissolved. in dry,

thiophene-free benzene, the solution is filtered from a 7 small amount of solid polymer and then concentrated by. distillation under reduced pressure until the product starts to crystallise. n-Hexane is added with stirring to aid the further separation of product and the large crystals of am-bis-(chloromethyl)-B-propiolactone are then collected by filtration and dried. The melting point is 36 C.

Example 3' in a slow stream of nitrogen-at a pressure of 0.1 mm. of

mercury to remove benzene and trace amounts of any other;v volatile materials. Thewhite solid polymer so obtained has asoftening point of about 280 C.,

Example 4 150 parts of aza-bis-(chloromethyl)-j3-propiolactone is heated to 40 C. out of contact with atmospheric moisture until completely molten and'-0.l.jpart of finely powdered potassium hydroxide is then added with stirring. Heating and stirring are continued at 40 C. for about 15 minutes and then the mixture is-heated to 50 C. The mixture soon becomes turbid owing to separationofpolymerand within 2 hours is completely solid. Heating is continued without agitation for a further 4hours at 50 C. and the product is then finally heated'at C. in a slow stream of nitrogen at a pressure of 0.1 mm. of mercury to remove traces of volatile material. The product is a tough, white solid' polyme'r which has asoftening pointof about 302 C. and gives a viscous melt from which may be spun filaments which are capable of being cold-drawn.

What we claim is:

1. Resinous.polyestersfhaving the recurring structural unit 2. A resinous homopolymer of aza-bis-(chloromethynp-propiolactone having'the recurring structural unit References-:Citedwin .-the-file, ofthis .patent' UNITED. STATES PATENTS 1,849,107 Moss Mar. 15,4932 2,580,714 Young, r m. 1, 1952 2,535,223 Caldwell Eeb. 12, 1952 2,658,055 Alderjson Nov. .3, 1953 

1. RESINOUS POLYMERS HAVING THE RECURRING STRUCTURAL UNIT 